Activity 02

Summary

• Continuing exploring the concept of $\sqrt{2}$ using proportions of an A4 sheet.
• understand mountan folds and valley folds
• make a model of octahedron skeleton and introduce the concepts of regular polyhedron and volume
• thread the octahedron model and hang it

Materials Required

• A4 sheets (about 3 sheets per student)
• 3"x3" squares of color origami paper. Each student needs 2 of each of 3 colors

Warmup - 10 mins

Review the masu box made during the [[activity-01]] and recap the relation between the side of the box to the area of the original square.

Activity - 60 mins

Exploration 1: Similarity of rectangles

How do you tell if two rectangles (this could be just a paper, or a book, or a phone) are similar?

• Case 1: A square and a rectangle with a long edge
• Case 2: A4 and A5 sheets

How do you define similarity?

Can you figure out how to tell if two rectangles are similar?

Have you noticed if we divide and A4 sheet into two equal parts along the long edge, we get a similar shape. Is that true for any size of paper? What is the magic portion of the A4 sheet that makes this possible?

Exploration 2: Mountain and valley folds

Make a waterbomb base. Mark the mountain and valley folds.

TODO

Exploration 3: Octahedron Skeleton

TODO